For Sol 159, we planned MAHLI imaging of one more rock outcrop before stowing the arm and driving about 1 meter backward. The goal of this short "bump" is to allow us to use the arm instruments to investigate spherical objects in the rock that some team members have interpreted as concretions--blobs of minerals that probably precipitated as water/brines cooled and/or evaporated. See examples of these concretions. The biggest challenge today was to return all of the data we need for Sol 160 planning, because the volume of data we expect to be able to return to Earth via the Mars Reconnaissance Orbiter is smaller than usual.